Apparatus for vapor generation

ABSTRACT

An apparatus for providing, in a continuous or intermittent manner, a superheated vapor of an organic liquid, such as methylene chloride, for reflowing plastic surfaces or causing a plastic material to flow onto a surface to create a film or coating thereon. The apparatus includes a tubular metal member defining a flow passage for both the liquid and gaseous phases of the liquid being vaporized. A vapor flow control member having a vapor flow orifice is provided at one end of the tubular member while the other end of the tubular member communicates with a source of organic liquid under pressure through an on-off valve. A source of electrical energy is connected in circuit with the tubular member through a switch operated concurrently with the valve whereby electrical current is caused to flow through the tubular member to heat the member to a temperature adequate to vaporize the liquid flowing therethrough. The tubular member is electrically and thermally insulated by a shield and a handle associated with the shield contains the valve and switch.

llnited States Patent 1191 Bennctt APPARATUS FOR VAPOR GENERATION [75]Inventor: Foster C. Bennett, Columbus, Ohio [73] Assignee: The DowChemical Company,

Midland, Mich.

[22] Filed: Sept. 15, 1972 [21] Appl. No.: 289,483

Related U.S. Application Data [63] Continuation-in-part of Ser. No.208,296, Dec. 15,

' 1971, abandoned.

[52] U.S. Cl 219/300, 219/272, 219/308, 219/373, 222/146 HE, 239/136[51] Int. Cl H05b 1/00, F22b 1/28, B05b 1/24 [58] Field of Search219/271-276, 219/300, 301, 362, 373, 296-299; 239/133,

I 135, 136, 137, 138; 222/146 HE [56] References 'Cited UNITED STATESPATENTS 383,536 5/1888 5 Newman ..'2l9/300UX 703,970 7/1902 'Ouain219/300 912,994 2/1909 Comrad 219/300 1,373,809 4/1921 Hadaway 219/3001,403,594 l/1922 Duo 219/300 1,575,152 3/1926 Di Battista 219/300 UX2,109,900 3/1938 Cohen 219/300 2,254,680 9/1941 Harvey 219/272 X2,277,291 3/1942 Blair 219/272 X 2,478,917 8/1949 Haim 219/300 X2,604,881 7/1952 Masopust 239/136 X 2,641,508 6/1953 Stoner et a1.239/137 X [4 1 Nov. 26, 1974 2,861,838 5 11/1958 Wyatt et a1. 219/2732,878,360 3/1959 Tavender et a1..v 239/133 X 3,686,475 8/1972 Mikkola219/272 3,718,805 2/1973 Posey 219/273 FOREIGN PATENTS OR APPLICATIONS482,715 4/1938 Great Britain 219/300 13,070 6/1933 Australia 219/271Primary Examiner-A. Bartis A ttomey, gent, or Firm Glwynn R. Baker [5 7ABSTRACT An apparatus for providing, in a continuous or intermittentmanner, a superheated vapor of an organic liquid, such as methylenechloride, for reflowing plastic surfaces or causing a plastic materialto flow onto a surface to create a film or coating thereon. Theapparatus includes a tubular metal member defining a flow passage forboth the liquid and gaseous phases of the liquid being vaporized. Avapor flow control member having a vapor flow orifice is provided at oneend of the tubular member while the other end of the tubular membercommunicates with a source of organic liquid under pressure through anon-off valve. A source of electrical energy is connected in circuit withthe tubular member through a switch operated concurrently with the valvewhereby electrical current is caused to flow through the tubular memberto heat the member to a temperature adequate to vaporize the liquidflowing therethrough. The tubular member is electrically and thermallyinsulated by a shield and a handle associated with the shield containsthe valve and switch.

2 Claims, 2 Drawing Figures APPARATUS FOR VAPOR GENERATIONCROSS-REFERENCE TO RELATED APPLICATION This application is acontinuation-in-part of my copending application filed Dec. 15, 1971,Ser. No. 208,296 now abandoned.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to anovel apparatus and-a process employing the apparatus for vaporizingfluids, such as volatile organic solvents or mixtures of solvents, toproduce superheated vapors of said fluid(s). More particularly, thepresent invention concerns a pressurized apparatus from whichsuperheated vapors of volatile organic solvents, generated within theapparatus, can be discharged in a controlled manner to impinge against aplastic surface, e.g., coating or surface of a body of plastic, toeffectuate the modification of the surface, viz., remove surfaceimperfections and defects, according to the vapor reflow principle or toflow a plastic powder'on a surface to createa film or coating thereon. I

Several embodiments ofapparatus within the scope of the presentinvention areillustrated in the Drawings:

charge orifice of the apparatus;

FIG. 2 illustratesanother embodiment of a vaporizer element of thepresent invention in cross-sectional view, which eliminates the effectof inductance when alternating current is employed.

DETAILED DESCRIPTION OF THE INVENTION In accordance with the presentinvention, having particular reference-to FIG. 1 of the Drawings, thereis provided a tubular member which is made ofa metal or an alloy of ametal having a resistance sufficient to convert electrical energy,supplied at low voltage and high amperage, into heat energy at a rate tosupply, within a length of several feet, the sensible heat necessary toraise the temperature'of the liquid to the boiling point, the heat ofvaporization of theliquid and the heat ofsuperheat of the vapor of theliquid to a prede' termined temperature. Connected to one end 11 of theto ambient atmosphere, as well as electrically insulating tubing 10 isprovided with a tubular electrical and heat insulating connector 20.Connector 20 is further connected by piping or flexible tubing 21 to apressurized container 22 which contains the liquid to be vaporized.

Pressure controls and a source of pressure, neither'of which are shown,are associated with the container '22. The power source 13 is alsoprovided with controls, transformers, and/or rectifiers, etc., asnecessary to produce the desired voltage and current to' provide thewattage to produce the desired temperature in the member 10.

The tubular member 10 is preferably provided, as shown, with a fluidflow control valve 23 to permit adjustment of the rate of flow and asimultaneously operable trigger mechanism or valve 24 to-permit off-onflow of fluid through tube 10 as well as an electrical switch whichsimultaneously permits flow of electricity to the member '10 when fluidis flowing and shuts off the flow 'of electricity to the member 10 whenfluid flow is interrupted.

. In operation of the apparatus illustrated in FIG. 1, a volatilizableliquid, for example, a halogenated hydrocarbon such as methylenechloride, is provided in container 22 and the container pressurized withfrom about 30 to about 200 pounds per square inch air pressure.'Thepower source is activated, and, for example, if methylene chloride is tobe delivered under 30-35 psig. as a superheated vapor at 400F. justoutside the nozzle 19, is adjusted to deliver about 30 volts at 75amperes of alternating current, converted from 220 volt source throughan isolated secondary of a transtubular member 10is an electric cable 12which prov vides one lead from the power source 13. Connected to theother end 14 of the member l'0-is another electric cable 1 5 whichprovides the second lead from'the' power source 13, thus completing anelectric'circuit from the power source 13, to the tubular member 10 (theelectrical resistance)- and back to-the power source 13. In theembodiment shown in FIG. 1, the tubula r member 10 is provided with ashielding member l6.which surrounds the member 10 and retains insulation17 in position to isolate member Whom the shield, thus insulating themember 10 from loss of heat former. Thermocouples, as at points x and yor by trial and error, simplify the adjustmentof the power source toprovide a superheated vapor of methylene chloride of a temperature ofabout 400F.; it being clearly understood the temperature of the vaporinside the apparatus will necessarily be higher than that outside thenozzle due to expansion and cooling phenomena of gases. The apparatusillustrated in FIG. 1 is capable of delivering several gallons an hourof such vapor continuously or intermittently. The preferred embodimentof the apparatus illustrated in FIG. 1' includes the control of thetemperature of the member 10 by using the signal generated by thethermocouples x and y to either shut off the current or turn it onintermittently.

It is one advantage of the apparatus of the present invention that oncethe current is turned off and simultaneously the flow'of fluid isstopped, the member 10 cools rapidly since it is of inconsequentialvolume, that is, its volume as a heat sink is less than the volume ofthe liquid in the tube. The apparatus can be even more rapidly cooledby'merely allowing a small quantity of liquid from the container 22 topass through the member 10 after the current-has been shut off at thetransformer controls, for example. Similarly, the member 10 heats uprapidly. Both of these features are important when the liquid beingheated is degradable by prolonged contact with high temperature.

3 heating member to eliminate substantially the effect of inductanceassociatedwith a current flowing through a coil. The tubular member 210is wound back over itself so that the current flowing at any instant inthe inner coil 210A is directly opposite that flowing in the 2108. Theoutlet end 211 is provided with a nozzel 219 and opposite ends of thecoil 210, i.e., 211 and 214, are provided with electrical connection 212and 215 which are connected to a power source, not shown. Similarly, thecoil 210 is connected at end 214 to a source of liquid not shown. Theapparatus may be, in all other aslarly, the coil rnay be employed toheat liquidsor generate vapors for chemical reactions.

' Having described my invention in general, the following examples areset forth to illustrate specific embodiments of the invention.

EXAMPLE 1 A type 316 stainless steel tube having an outside diameter ofV4 inch and a wall thickness of 0.028 inch was close wound on a 2 inchmandrel to provide thirteenturns then a spaceequal to about two turnsfollowed by fourteen turns. The coil was started by bringing a pointabout five inches from one end into a groove in the mandrel near itscenter, and bringing the tubing to the rear of the mandrel along agroove to the point of beginning of the coil forming section. The coilsowound was insulated between each turn with a disc of insulatingmaterial, compressed asbestos, capable of withstanding l,200F.temperatures. The coil was also insulated along and about its peripheraldimensions with an alumina-silica ceramic fiber insulation (e.g.,Fiberfrax or Kaowool) of about inch. A 3% inch OD tube of Type 304stainless steel was placed about the assembly, closed at the rearwardend and provided with an end cap to receive the discharge end of thetube and aid in holding the tube within the shield assembly. The shieldwas provided with a handle of metal to surround the inlet end of thetube. The space between the tube and the handle was insulated. The inletend of the tube was provided with a fitting to receive a Teflon nipple,to which was fitted a liquid control valve. The leads from a KVAalternating current isolated secondary 220 volt transformer were brazed,oneto the tube and one to the handle. A container provided with an airpressure system was connected to the control valve. Upon pressurizationof the container which contained methylene chloride, and activation ofthe transformer to deliver 30 volts and .75 ,amperes, the methylenechloride flowing into the tube was converted into a vapor which had atemperature, upon leaving thenozzle of about 400F.

The following table illustrates the versatility of the apparatusof FIG.1 to vaporize various requirements of a methylene chloride compositionemployed to flow an acrylic paint surface.

Watts at Indicated Ave. Voltage Flow Rate Gallons/Hour 600ll6.5 .1200/22 moo/27.5 2400/33 Juno/38.5 3600/44 4200/4 with an acrylic lacquerof the type used to paint automobiles and which painted panel had beenlightly sanded, removed surface imperfections.

The apparatus illustrated in FIG. 1 can also be operated from a V sourceusing a five KVA transformer 32 volts isolated secondary to supply up to2 gallons per hour of the methylene chloride composition at 400F.

I claim:

1. An apparatus for converting a volatilizable organic liquid or mixtureof liquids into superheated vapors which consists essentially of:

a tubular metal member which is electrically conductive but has aresistance to the flow'of an electrical current and which member definesa flow path for the liquid to be vaporized andfor the vaporized liquid,7

a vapor flow control member at one end of said tubular metal member,said vapor control member having a vapor outlet orifice, a manuallyactuated open-close liquid flow control member at the opposite end'ofsaid tubular metal member for selectively controlling liquid flow intosaid tubular metal member,

a source of electrical energy connected at a pair of spaced points tosaid tubular metal member by means arranged to be controlledconcurrently with and in on-off corresponding relationship with saidliquid flow control member whereby electrical energy is causedto flowthrough a predetermined segment of said tubular metal member to heat thetubular metal member to a temperature to vaporize the liquid flowingtherethrough,

a source of volatilizable organic liquid connected in flow communicationwith the tubular metal member through said liquid flow control member,said source of liquid being under superatmospheric pressure whereby theliquid therein is caused to flow into the tubular metal member when theliquid flow control memberis opened,

the tubular metal member being heated to such a temperature and thelength ofthe heated portion of the tubular metal member, the bore of thetubular metal member and the orifice of said vapor flow control memberbeing of such a size relative to each other such that the liquidsupplied under pressure into the tubular metal member will vaporize andsaid'vapor will be heated to above its boiling point at a rate tomaintain a pressure of vapor at,

the vapor flow control member sufficient to propel the vapors from theapparatus at least about one foot. I

said means connecting said electrical energy source a connectorconnecting said tubular metal member through said liquid flow controlmember to said source of vaporizable organic liquid,

said tubular metal member, vapor flow member, and

said liquid flow control member being capable of withstandingsuperatmospheric pressures and a temperature of l,200" F. and saidelectrical energy connectors and switch being capable of withstandingfive to ten KVA alternating current power,

said tubular metal member electrically and thermally insulated by ashield and a handle associated with said shield and containing theliquid flow control member and the switch, said vapor control memberprojecting from one end of the shield.

2. An apparatus for converting a volatilizable organic liquid ormixtureof liquids into superheated vapors which consists essentially of:

a tubular metal member which is electrically conductive but has aresistance to flow of an electrical current and which member defines aflow passage for carrying both liquid and gaseous forms of said liquidto be vaporized,

a vapor flow control member at one end of said tubular metal memberhaving a vapor outlet orifice,

a manually operated open-close liquid flow control member at the otherend of said tubular metal member for controlling liquid flow into thetubular metal member,

said tubular metal member being disconnectable and removable from saidflow control member,

electrical energy connectors in current flowing contact with therespective ends of said tubular metal member, 7

an electrical current source in circuit with said electrical energyconnectors and a switch associated with said liquid flow control memberin concurrent similarly functioning open-close relation to said liquidcontrol member for controlling application of energy to said connectorsfrom said source whereby electrical current is caused to flow throughthe tubular member to heat the member to a temperature adequate tovaporize the liquid flowing therethrough,

a connector associating said tubular metal member through said liquidflow control member to a source of vaporizable organicliquid and meansassociated with the source for causing the liquid to flow into thetubular metal member when the fluid control member is opened,

said tubular metal member, vapor flow member, and said liquid flowcontrol member being capable of withstanding superatmospheric pressuresand a temperature of 1,200F. and said electrical energy connectors andswitch being capable of withstanding tive to ten KVA alternating currentpower,

said tubular metal member electrically and thermally insulated by ashield and a handle associated with said shield and containing theliquid flow control member and the switch, said vapor control memberprojecting from one end of the shield.

1. An apparatus for converting a volatilizable organic liquid or mixtureof liquids into superheated vapors which consists essentially of: atubular metal member which is electrically conductive but has aresistance to the flow of an electrical current and which member definesa flow path for the liquid to be vaporized and for the vaporized liquid,a vapor flow control member at one end of said tubular metal member,said vapor control member having a vapor outlet orifice, a manuallyactuated open-close liquid flow control member at the opposite end ofsaid tubular metal member for selectively controlling liquid flow intosaid tubular metal member, a source of electrical energy connected at apair of spaced points to said tubular metal member by means arranged tobe controlled concurrently with and in on-off corresponding relationshipwith said liquid flow control member whereby electrical energy is causedto flow through a predetermined segment of said tubular metal member toheat the tubular metal member to a temperature to vaporize the liquidflowing therethrough, a source of volatilizable organic liquid connectedin flow communication with the tubular metal member through said liquidflow control member, said source of liquid being under superatmosphericpressure whereby the liquid therein is caused to flow into the tubularmetal member when the liquid flow control member is opened, the tubularmetal member being heated to such a temperature and the length of theheated portion of the tubular metal member, the bore of the tubularmetal member and the orifice of said vapor flow control member being ofsuch a size relative to each other such that the liquid supplied underpressure into the tubular metal member will vaporize and said vapor willbe heated to above its boiling point at a rate to maintain a pressure ofvapor at the vapor flow control member sufficient to propel the vaporsfrom the apparatus at least about one foot, said means connecting saidelectrical energy source to said tubular metal member includingconnectors in current flowing contact with the respective ends of saidtubular metal member, said electrical energy source being connected incircuit with said connectors and said connecting means further includinga switch associated with said liquid flow control member in concurrentsimilarly functioning open-close relation to said liquid control memberfor controlling application of energy to said connectors from saidsource whereby electrical current is caused to flow through the tubularmember to heat the member to a temperature adequate to vaporize theliquid flowing therethrough, a connector connecting said tubular metalmember through said liquid flow control member to said source ofvaporizable organic liquid, said tubular metal member, vapor flowmembeR, and said liquid flow control member being capable ofwithstanding superatmospheric pressures and a temperature of 1,200*F.and said electrical energy connectors and switch being capable ofwithstanding five to ten KVA alternating current power, said tubularmetal member electrically and thermally insulated by a shield and ahandle associated with said shield and containing the liquid flowcontrol member and the switch, said vapor control member projecting fromone end of the shield.
 2. An apparatus for converting a volatilizableorganic liquid or mixture of liquids into superheated vapors whichconsists essentially of: a tubular metal member which is electricallyconductive but has a resistance to flow of an electrical current andwhich member defines a flow passage for carrying both liquid and gaseousforms of said liquid to be vaporized, a vapor flow control member at oneend of said tubular metal member having a vapor outlet orifice, amanually operated open-close liquid flow control member at the other endof said tubular metal member for controlling liquid flow into thetubular metal member, said tubular metal member being disconnectable andremovable from said flow control member, electrical energy connectors incurrent flowing contact with the respective ends of said tubular metalmember, an electrical current source in circuit with said electricalenergy connectors and a switch associated with said liquid flow controlmember in concurrent similarly functioning open-close relation to saidliquid control member for controlling application of energy to saidconnectors from said source whereby electrical current is caused to flowthrough the tubular member to heat the member to a temperature adequateto vaporize the liquid flowing therethrough, a connector associatingsaid tubular metal member through said liquid flow control member to asource of vaporizable organic liquid and means associated with thesource for causing the liquid to flow into the tubular metal member whenthe fluid control member is opened, said tubular metal member, vaporflow member, and said liquid flow control member being capable ofwithstanding superatmospheric pressures and a temperature of 1,200*F.and said electrical energy connectors and switch being capable ofwithstanding five to ten KVA alternating current power, said tubularmetal member electrically and thermally insulated by a shield and ahandle associated with said shield and containing the liquid flowcontrol member and the switch, said vapor control member projecting fromone end of the shield.